Thermally expandable transition piece

ABSTRACT

A gas turbine engine (GTE) including a thermally expandable transition piece is disclosed. The GTE includes at least a combustor section having a combustor sleeve, also known as top hat, and a transition piece. The transition piece includes a transition duct having an upstream end, a downstream end, a outer surface and a forward end face. The transition piece also includes one or more struts selectively attached to the transition duct proximate to the upstream end. The strut extends radially upward from the outer surface, and axially outward beyond the forward end face for interfacing the strut with at least a portion of the combustor sleeve.

TECHNICAL FIELD

The present disclosure relates generally to gas turbine engines, and more particularly, to a gas turbine engine transition piece and its support assemblies.

BACKGROUND

Gas turbine engines operate to produce mechanical work or thrust. One type of gas turbine engine is a land based engine coupled to a generator for the purposes of generating electricity. Gas turbine engines have at least a compressor section, a combustor section, and a turbine section. The combustor section may include a plurality of combustors arranged in an annular array around a rotor. The turbine section includes alternating rows of stationary airfoils and rotating airfoils. In operation, air is drawn in through the compressor section, where it is compressed and the driven towards the combustor section. The air may then be mixed with fuel to form an air/fuel mixture. In the combustor, the mixture may be ignited to form a working gas. A transition duct may be provided for each combustor to route the working gas to the turbine section. Each transition duct includes an inlet (upstream) end, an exit (downstream) end. To support the transition duct in the gas turbine, fixed support assemblies including support brackets and various seals have been provided at both the downstream and upstream ends for attaching the same to structures in both the turbine and combustor sections, respectively. However, concerns arise as these support assemblies suffer from large thermal stresses at various locations during the gas turbines operation, thereby restricting thermal growth of hot transition ducts. Therefore, there remains a need for a means to support the transition duct that can minimize the above concerns, and allow for thermal growth.

SUMMARY

In one embodiment, a gas turbine engine with a thermally expandable transition piece is described, and which comprises at least a combustor section. The combustor section includes a combustor sleeve and a transition piece. The transition piece includes a transition duct having an upstream end, a downstream end, an outer surface and an end face. The transition piece further includes a strut extending radially outward from the outer surface at the upstream end for interfacing with at least a portion of the combustor sleeve.

In another embodiment, a thermally expandable transition piece assembly for a gas turbine engine is described. The transition piece includes a transition duct having an upstream end for operatively connecting to a combustor section of a turbine, and a downstream end for operatively connecting to a turbine cylinder section of a turbine. The transition piece further includes a strut selectively attached at the upstream end, and extending radially upward from an outer surface of the transition duct, and axially outward beyond an end face at the upstream end for operatively connecting the transition piece assembly to the combustor section of a turbine.

In yet a further embodiment, a method of manufacturing a thermally expandable transition piece is disclosed. The method includes the step of selectively attaching a strut to a surface of a transition duct at an upstream end of the transition duct, the strut extending radially upward from the surface and axially outward beyond an end face at the upstream end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a transition duct mounted to a combustor section with a mounting assembly known in the prior art;

FIG. 2 illustrates a cutaway perspective view of a gas turbine engine including a thermally expandable transition piece in accordance with the disclosure provided herein;

FIG. 3 illustrates a perspective view of an embodiment of a thermally expandable transition piece in accordance with the disclosure provided herein;

FIG. 4 illustrates an embodiment of the thermally expandable transition piece engaged to a structure in the combustor section of the gas turbine engine in accordance with the disclosure provided herein;

FIG. 5 is a block diagram of a method for manufacturing a thermally expandable transition piece in accordance with the disclosure provided herein; and

FIG. 6 is a block diagram of a method for assembling a gas turbine engine in accordance with the disclosure provided herein.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the subject matter herein only and not for limiting the same, FIG. 2 shows a perspective view of a gas turbine engine (GTE) depicted generally at 100 with a thermally expandable transition piece 200. The GTE 100 generally may include at least an inlet casing section 120 operatively connected to a compressor casing section 130; the compressor casing section 130 may be operatively connected to a combustor section 140; the combustor section 140 may be operatively connected to a turbine cylinder section 150; the turbine cylinder section 150 may be operatively connected to an exhaust cylinder section 160; the exhaust cylinder section 160 may be operatively connected to a manifold section 170.

With reference to FIGS. 3, a perspective view of the thermally expandable transition piece 200 is shown. In one embodiment, the transition piece 200 includes at least a transition duct 210 having a generally tubular body with a generally semi-circular shape at an upstream end 212, to receive hot gases from an associated combustor of a gas turbine (e.g., a can-annular combustor), and a generally semi-rectangular shape at a downstream end 214, to discharge the gases to an associated stage of the gas turbine. The transition duct 210 further includes an outer surface 216, and a forward end face 218. The thermally expandable transition piece 200 may further include one or more struts 300 selectively attached to an outer surface 216 of the transition duct 210 proximate to the upstream end 212. In the embodiment of FIG. 3, three struts 300 are attached at the upstream end 212; however, it should be appreciated that more than three struts 300 may be attached to the thermally expandable transition piece 200. When selectively attached to the transition duct 210, the strut 300 may extend radially outward (protruding upwardly) from the outer surface 216 at the upstream end 212. Additionally, at least a portion of the strut 300 may extend axially outward beyond the forward end face 218.

With continued reference to FIG. 3, the struts 300 may be spaced apart in a uniform manner around the perimeter of the transition duct 210. For example, FIG. 3 illustrates the struts 300 being spaced an equidistance apart from one another. However, it should be appreciated that the struts 3000 may be spaced apart in any manner chosen with sound judgment. In yet a further embodiment, the struts 300 may be offset from one another around the perimeter of the transition duct 210 such that the length of the portions of the struts 300 extending beyond the forward end face 218 differs. The struts 300 may be selectively attached to the outer surface 216 by an attachment means (not shown), such as by bolts, fasteners, pins, and/or weld. Additional examples of the attachment means may include a nut-bolt combination, rivet, screw, nail, or other suitable mechanical fastening devices known to persons of ordinary skill in the art and capable of selectively attaching the strut 300 to the transition duct 210.

In a further embodiment, the strut 300 may be integrally formed with the transition duct 210. As used herein, integrally formed means to couple such that the pieces are relatively permanently joined. The strut 300 and the transition duct 210 may also be fabricated, molded or machined as a unitary structure, as compared to being separate components mounted together, through welding, fastening mechanical engagement or any means known to persons of ordinary skill in the art. In an embodiment where the struts 300 are not integrally formed with the transition duct 210, the strut 300 may include a lower end face 310 adapted to selectively attach the strut 300 to the outer surface 216 of the transition duct 210, and an upper end face 320 adapted to interface with a combustor sleeve 400 or wear pad 410 (FIG. 4) of the combustor section 140. The lower end face 310 may have a profile adapted to interface with the outer surface 216, e.g., an arcuate profile. Additionally, the upper end face 320 may have a profile adapted to interface with the combustor sleeve 400 or wear pad 410. The profile of the lower end face 310 and the upper end face 320 may be similar in one embodiment, or they may differ in a further embodiment such that the both profiles curve in opposed directions.

The strut 300 may have a thickness that provides for adequate strength to support the transition piece 200, without restricting flow during operation of the GTE 100. In one embodiment, the surface area for the lower end face 310 and the upper end face 320 may differ. For example, as illustrated in FIG. 4, the upper end face 320 surface area is less than the surface area of the lower end face 310. The strut 300 may have a generally arcuate profile such that the surface area of the lower surface 330 and upper surface 340, between the lower end face 310 and upper end face 320, has no angles. In a further embodiment, the surface area of the strut 300 may have one or more angles between the lower end face 310 and upper end face 320. Additionally, the strut 300 may also be symmetrical or asymmetrical.

With continued reference to FIG. 3, and now FIG. 4, the combustor sleeve 400, also referred to as “top hat” in the art, includes an interior compartment 420 configured to house at least a portion of a combustor 500 therein, and an exterior 430 having one or more flanges 440 protruding therefrom. The flange 440 may be adapted for interfacing the combustor sleeve 400 with one more components of the GTE 100, and for at least partially restricting movement of the combustor sleeve 400. The interior compartment 420 may be sized such that at least a portion of the transition piece 200, (e.g., strut 300) may be received therein. In the embodiment of FIG. 4, the strut 300 extending from the transition duct 210 is shown as being partially disposed within the interior compartment 420 and interfacing with an interior surface 425 of the interior compartment 420.

The wear pad 410 may be an adaptable plate sized to fit within the interior compartment 420, and be made from hard materials, such as a metallic or ceramic material, e.g., nickel or cobalt, or a softer material with hard facing, e.g., chromium carbide, flame sprayed, or any other material chosen with sound judgment and capable of interfacing with the interior compartment 420 and/or strut 300, managing contact stress, and maintaining a form of structural integrity such that the wear pad 410 or portions thereof have little to no chance of separation during operation of the GTE 100. The wear pad 410 may be constructed from a material different from that of the strut 300 and/or the interior compartment 420. The wear pad 410 may also have a low profile and be adapted to conform to the shape of the interior compartment 420, e.g., an arcuate shape. The wear pad 410 may be selectively attached to the interior surface 425 by an attachment means similar to the attachment means described herein. The attachment means should allow for no separation of the wear pad 410 from the interior compartment 420 during operation of the GTE 100. Additionally, the attachment means may further assist in facilitating the replacement of the wear pad 410 when its surface area begins to wear down or simply needs to be replaced. In a further embodiment, multiple wear pads may be stacked within the interior compartment to provide additional interfacing support, or facilitate the replacement of a worn wear pad 410.

In yet a further embodiment, the wear pad 410 may be integral with the interior compartment 420. Additionally, the wear pad 410 may extend to cover the interior surface 425, or may have a defined area thereby distinguishing the wear pad 410 surface from any other surface of the interior compartment 420. In yet a further embodiment, at least a portion of the wear pad 410 surface may be grooved, textured, or have a configuration chosen with sound judgment to allow for interfacing the wear pad 410 with the strut 300, while maintaining the integrity of the wear pad 410. In yet a further embodiment, the wear pad 410 may be a substrate or formed from a substrate applied to the interior surface 425 by an additive manufacturing process, the result of which manages contact stress. The wear pad 410 may further allow for the transition piece 200 to be frictionally fitted within the interior compartment 420, while allowing for thermal expansion. Additionally, the wear pad 410 may be lubricious to further facilitate interfacing and thermal expansion.

With continued reference to the figures, and now FIG. 5, a block diagram of a method 1000 for manufacturing a thermally expandable transition piece 200 in accordance with one embodiment is provided. In step 1010, selectively attaching the strut 300 to the outer surface 216 of a transition duct 210 at an upstream end 212 of the transition duct 210 by the attachment means disclosed herein. In yet a further embodiment, prior to step 1010, the method 1000 may include step 1020 for removing an assembly for mounting the transition duct 210. In this step, removal of the prior art assembly (FIG. 1), may be necessary when retrofitting the struts 300 to the transition duct 210. In step 1030, selectively attaching a plurality of struts 300 to the transition duct 210.

With continued reference to the figures, and now FIG. 6, a block diagram of a method 2000 for assembling the GTE 100, or more particularly, the combustor section 140 of the GTE 100 with the transition piece 200 in accordance with one embodiment is provided. In step 2010, operatively interfacing the thermally expandable transition piece 200 to a structure (e.g., combustor sleeve 400 or wear pad 410) in the combustor section of the GTE 100. In this step, an assembler may shift the transition piece 200 towards the combustor sleeve 400 such that at least a portion of the transition piece 200, e.g., the strut 300, may be received within the combustor sleeve 400. At this point, the strut 300 may be interfacing with the interior surface 425 or wear pad 410.

While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternative to those details could be developed in light of the overall teachings of the disclosure. For example, elements described in association with different embodiments may be combined. Accordingly, the particular arrangements disclosed are meant to be illustrative only and should not be construed as limiting the scope of the claims or disclosure, which are to be given the full breadth of the appended claims, and any and all equivalents thereof. It should be noted that the term “comprising” does not exclude other elements or steps, and the use of articles “a” or “an” does not exclude a plurality. 

We claim:
 1. A gas turbine engine comprising: a gas turbine housing having at least a combustor section; wherein said combustor section includes a sleeve and a transition piece, the transition piece including: a transition duct having an upstream end, a downstream end, an outer surface and an end face; and a strut extending radially outward from the outer surface at the upstream end, said strut interfacing with at least a portion of the sleeve.
 2. The gas turbine engine of claim 1, wherein the transition piece includes a plurality of struts extending radially outward from the outer surface at the upstream end.
 3. The gas turbine engine of claim 2, wherein each of said plurality of struts interfaces with at least a portion of the combustor sleeve.
 4. The gas turbine engine of claim 3, wherein the plurality of struts are equidistantly spaced around a perimeter of the transition duct.
 5. The gas turbine engine of claim 2, wherein at least a portion of one of the plurality of struts extends axially outward beyond the end face of the transition duct at the upstream end.
 6. The gas turbine engine of claim 1, further comprising a wear pad interposed between the strut and the combustor sleeve for interfacing the transition piece with the combustor sleeve.
 7. A thermally expandable transition piece assembly for a gas turbine engine comprising: a transition duct having an upstream end for operatively connecting to a combustor section of a turbine, and a downstream end for operatively connecting to a turbine cylinder section of a turbine; and a strut selectively attached at the upstream end, said strut extending radially upward from an outer surface of the transition duct, and axially outward beyond an end face at the upstream end for operatively connecting the transition piece assembly to the combustor section of a turbine.
 8. The assembly of claim 7 wherein a plurality of struts selectively are attached at the upstream end, said plurality of struts extending radially outward from the outer surface of the transition duct, and axially outward beyond the end face at the upstream end.
 9. The assembly of claim 8, wherein the plurality of struts are integrally formed with the transition duct.
 10. The assembly of claim 8, wherein the plurality of struts are spaced equidistantly apart around the perimeter of the transition duct.
 11. A method of manufacturing a thermally expandable transition piece comprising: selectively attaching a strut to a surface of a transition duct at an upstream end of the transition duct, said strut extending radially upward from the surface and axially outward beyond an end face at the upstream end.
 12. The method of claim 11 further comprising: prior to selectively attaching said strut to a surface of the transition duct, removing a transition duct mount from the transition duct.
 13. The method of claim 11 further comprising: selectively attaching a plurality of struts to the upstream end, said plurality of struts extending radially upward from the surface of the transition duct and axially outward beyond the end face at the upstream end.
 14. The method of claim 12 further comprising: selectively attaching a plurality of struts to the upstream end, said plurality of struts extending radially outward from the surface of the transition duct and axially outward beyond the end face at the upstream end.
 15. A method for assembling a gas turbine engine with the thermally expandable transition piece according to claim 13: operatively interfacing the thermally expandable transition piece to a structure in a combustor section of the gas turbine engine.
 16. The method of claim 15, wherein the structure is a combustor sleeve.
 17. The method of claim 16, wherein at least one of the plurality of struts interfaces with the combustor sleeve.
 18. The method of claim 17, further comprising a wear pad interposed between the at least one of the plurality of struts and the combustor sleeve.
 19. The method of claim 17, wherein the plurality of struts interfaces with the combustor sleeve.
 20. The method of claim 19, further comprising a wear pad interposed between each of the plurality struts and the combustor sleeve. 